The present invention relates to the grasping of articles, and more particularly to a gripper having spring-loaded jaws, for quickly and reliably grasping and releasing articles compatible with the jaws, e.g., box-like articles. This type of gripper is used, for example, in an automated handling system. In general, the present invention relates to the grasping of articles compatible with the jaws of the gripper. However, for ease of discussion, reference to tape cassettes will be made herein.
Automated handling systems commonly are used to move an article from one point to another. For example, it commonly is desired to retrieve a particular cassette from among a library of cassettes, obtain information from the cassette, and then return the cassette to its designated position in the library. Sometimes the constant retrieval and return of cassettes is required; thousands of consecutive load and unload operations may be required to be performed in a single day. Thus, a gripper assembly for an automated handling system must be capable of quickly and reliably grasping and releasing cassettes.
One recently developed gripper grasps a box-like article between a stationary plate and a movable flat spring. This gripper is disclosed in U.S. Pat. No. 4,846,619 assigned to the same assignee as the present invention. The gripper is attached to an accesser which moves the gripper toward a targeted article contained in a storage bin or toward a destination point, e.g., a tape transport device. This gripper has many advantages in the handling of video cassettes. However, due to its construction, the gripper has a low degree of freedom with respect to the targeted article and to the destination point, and the gripper must be extremely accurately positioned before the article can be loaded or unloaded. Thus, the accesser has the burden of very accurately aligning the gripper with respect to a targeted article or destination point.
It is, of course, important that information on tape be protected. Thus, care must be taken to limit wear on the cassette housing. Physical rubbing and other touching of the cassette by the gripper should be minimized. Also, it is desirable for the gripper to have a high degree of freedom, so that even if a cassette is misaligned in its storage bin, the gripper is still able to function quickly and reliably.